CSS 2.1, 10.6.4 says:
[...] the static position for 'top' is the distance from the top edge
of the containing block to the top margin edge of a hypothetical box
that would have been the first box of the element if its 'position'
property had been 'static' and 'float' had been 'none'.
I suggest we add /and 'clear' had been 'none'/ to that.
The suggested addition matches what most UAs do, with the exception
of IE7, but IE8 beta 1 seems to match other UAs now. See [1] for
test details.
Thanks,
Mats Palmgren
[1]
https://bugzilla.mozilla.org/show_bug.cgi?id=390516